Shell inspection apparatus



Aug. 19, .1952

A. F. DAUBER ETAL SHELL INSPECTION APPARATS 5 Sheets-Sheet -Il.

'Filed Jung 1, 1951 .1N 4 im@ Ww MEEM E OBNo N TUGJ m MMWR. T VFES /N mHE N e Pwm a mTH DNC AA8 h uN v ,Aw M .A :R E 2 N e TU J O 7 d J MAMR.. T 0 VDF. N 6 v NF. S I EL 2 n WR/M. l. @w LOA m QQ orw N n 5 AAB A FH DAUBER ET AL SHELL. NSPECTI'QN APPARATUS Aug. 19,l 1952 y Flled June 1 1951 Aug. 19, 1952 A. F. DAUBER ETAL SHELL INSPECTION APPARATUS 5 Sheets-Sheet 5 Filed June l, 1951 Allg. 19, 1952 F. DAuBl-:R ET AL 2,607,480

SHELL INSPECTION APPARATUS Filed June l, 1951 5 sheets-5116er 4 L O, NVENTORS ADOLPH F. DAUBER, ANTOINE F. GAGNE JR. O

l By aoHARLEsR oHn/soM J0 f3 5 WfW/w '.9 12 E' /f/f Aam A TTORNE YS Aug. 19, 1952 A. F. DAUBER ET Al.-

SHELL INSPECTION APPARATUS Filed June l 1951 5 Sheets-Sheet 5 .l a. ,mm fum SRE.,S M nvOAENN. R NU A0 T EMG T WEFM d. .A IHEE d PNL mmm 4M www N A8 Y B Patented Aug. 19, 1952 UNITED STATE SHELL INSPECTION APPARATUS Adolph F. Dauber, Elam, Pa., Antoine `F.`"Grag`ne, Jr., Stratford, Conn., and Charles R. Johnson, 1 Glenn Mills, Pa., assignors to E. I. du Pont deA` Nemours & Company, Wilmington, Del., a corporation ol Delaware Application Julie 1, 1951,seriai No. 229,374

The present invention relates to an apparatus for the sorting and inspection of blasting cap shells. More particularly, this invention provides an assembly adapted to sort and remove blasting `cap shells, which'are not up to standard, efliciently and rapidly, and with a minimum amount of human supervision.

Blasting caps are assembled by the millions annually for commercial users of explosives. Because of their basic function of initiating the main charge, blasting caps must be of high quality and of uniform standard. The blasting cap shell, or container for the explosive charge and initiating means, is an important element in determining the performance and utility of blasting caps since it is the shell which possesses the rigidity and strength necessary to maintain the various units of a blasting cap in the proper relationship despite rough handling, and which protects the units from contact with moisture and other deleterious substances.

The blasting cap shells most predominantly used by the industry are metallic, although recently attention has been given to the use of various plastics. The metallic caps are generally fabricated vby cold-drawing copper or aluminum to form tubular containers having one end thereof closed.

In the manufacture of blasting cap shells by the above procedure, or by substantially any alternative procedure, it is inevitablethat a certain percentage of the shells thus produced will contain defects which render them unsuitable for use. 'I'hese defects may be extremely difcult to detect, particularly by visual means. 'I'he imperfections may consist of such things as slight perforations in the walls or end closure, unevenness of the open ends, splits in the walls, weakened side walls, etc. In addition to the above named imperfections, a frequent cause of difculty is found in shells of uneven length. In some processes shells are loaded and assembled mechanically, and a, lack of uniformity in length may produce blasting caps which will not re. If the shell is too short, the bridge Wire. may be broken by contact with the pressed charge of explosive, or the `closure plug may not be sufiiciently anchored to prevent later movement. On the other hand, if the shell is too long, the bridge wire may be too far from the explosive charge to ignite it, or the loading mechanism may become jammed.

In the past, shell inspection has been performed by a battery of skilled workers who had to check each shell individually. It is natural that in handling a large number of shells, most of which are satisfactory, an appreciable number of slightly defective shells will pass this inspection and later cause diilculty. Due to the small sizes of the various cap shells, this manual han- 'dlingand inspection is extremely fatiguing and bothersome, as well as costly.

It is, therefore, an object of the present invention to provide an apparatus which will eliminate the need of individual handling of blasting cap shells. It is a further object of the presentinvention to provide an apparatus which will efciently and rapidly reject imperfect blasting cap shells. An additional object of the present invention is to provide an apparatus for the inspection and sorting of blasting cap shells which requires av minimum amount of human supery vision. Additional objects will become apparent vas the inventionis further described.

We have found that the foregoing objects may -be achieved by providing, in combination, a means for separating and aligning individual shells from a jumbled mass of shells; a means for subjecting each shell to a mechanical test for perforations, splits, unevenness, etc., a means of rejecting defective shells and passing satisfactory shells, a means for determining which shells are of nonuniform length and of removing them, and a means of presenting the shells for a iinal visual inspection in such manner that any previously undetected aws are attention directing.

An apparatus which is adapted to provide the necessary means is fully illustrated in the accompanying drawings, and the present invention may be more completely described by reference to the various drawings. It is to be understood that'many of the elements making up the complete assembly are capable of replacement with alternative elements differing in operation but not in function. The drawings, therefore, are intended as illustrative, and not as limiting the present invention.

In the drawings,

Figure 1 represent-s a frontal view of an assembled inspection apparatus; and

Figure 2 represents a top view of the same assembly.

Figure 3 represents a frontal view of the separating and aligning unit of the assembly; and

Figure 4 represents a detailed View of a section of the separating and aligning unit of the assembly; while Figure 5 represents a side section of the separating and kaligning unit, and a detail of an inspection element;

Figure 6 represents an embodiment of a height inspection unit used in the present assembly, and also shows the 'differential belt used to rotate the shells slowly'as they pass before the operator.

3 Using the line F-F as the floor level, I is a supporting framework of steel for the working parts of the apparatus, 2 is a floor level receiving bin for uninspected shells, 3 is the sorting assembly which Valso partiallyrk inspects the shells, 4 isv a reject bin, 5 is the visual inspection assembly,

and 6 is the container for the satisfactory, in-Y spected shells. Y

As shown in Figures 1 and 2,. the shells. are

conveyed from the receiving ybin V2to the sorting-v assembly 3 by means of an endlessconveyor chainl tinuously and is guided by means o sprocket wheels II and drive sprocket I2 which projects from the sorting assembly 3. Thesorting agsembly 3,r the conveyorzvchain 7, and the endless chain-"Saredriven by means of. an electricmotor I3 andI gear reducerv (not shown) through the chain Iii. After the` shells pass7 the vinspection assembly 5, they drop into the receiving funnel l,.from which. they pass to the container 6. V

The sorting.assembly13- illustrated in Figures `3, 4f. and- '5; consistsprimarily of a. drum I6 containing ak number of helical grooves II, a face plate. I8 containing slanted openings I9 to permit the Vpassage of the-shellsvfrom the drum I6 to matching labyrinth sectionswhere the shells are aligned and partially tested. The labyrinth sec- .tionsall have a cover plateY 2l. which is secured with quick-oper'iing: screw fasteners 22v for speedy jam clearance.-v Ther sorting drum l5 and the face plate I8 containing the labyrinthsections 26 are supported `by means of anv aXle shaft. 23 which is-rinnturnlnsupported by means of front bearings d and rear bea-rings (not shown) located-inaninwardly projecting hollow sleeve of the sorting `assembly housing 2.5,v the housing being fastenedto'the support frame I. The axle 23 contains passageway 25 leading from an. outside vacuum connection 21 tomultiple vacuum test units 28.. Each. vacuum test unitv 28 consists o passageway 29. leading to a spring loaded poppet valve n311V which islactuated by means-of cam actuated tappet 3|.,governed by the groove 32 in the ixed cam ring 33. V:tI- l isa chamber: between poppet v-alve 30 and poppet valve 35,. the latter beingactuated. by means of tappet 3B, cam groove 31 andxed cam. ring 38. Passageway 39 leads to the outside of the assembly (open air), and passageway 4G leads to a resilient sealing disc 4I. Drive sprocket I2" is connected to a projecting end of theaxle shaft 23. f

The labyrinth sections 2li consist of machined pieces 42'to 5i) so arranged as toform passageways for the shell to travel, a movable escapement jaw 5I connectedv by shaft 52( through spring 68 to cam roller 53 operating in cam groove 54 of cam ring 55, and a shell alignment pin 56 projecting from piece 42. cover plate ZI contains shell guiding nozzle 57 to direct the shell yfrom the labyrinth section 20 to the carrying pin I0 of the'chain 9.

Thevisu'al inspection assembly 5 includes electric micro-switches 58, 59 and 60, and their. respective contact arms 6I, 62 and 63; shell'rotating belt vSIT, and inspection table 65. At the portion of the assemblyimder arm .Ii-2 ofmicroswitch 59 is the. shell ramp 66.

' fnoperation, the shellsV aremanually or mechanically dumpediinto the` receiving bin 2 after they. have., been.. fabncatedjand .washed to re- The labyrinth move loose particles. By means of the conveyor chain l, which contains a plurality of bucket shaped scoops, shells are continuously lifted from the bin 2;. and dropped into. the sorting drum I6 through the opening El' of the sorting assembly housing 25. The .rotation of the drum IB tumbles the shells at the bottom, and lls the helical grooves I'I. The grooves are so machined. that shells which are not horizontal with respect to the grooves I'I are not retained thereby, but will be knocked out by other shells in the drum.

Y As.v the drum Ifrotates in a clockwise direction,

long, or has not fully cleared the opening is,

damage or jammingy of the jaw is prevented by the spring I8`which permits the Cam roller' to move, without moving shaft 52. The late timing and the angle between 5I and IQ serve to help separate the shell in 5I from the one following in I A shellvvhich has fully entered the jaw 5i' slides to the orientation pin 56 of piece d2. The distance between the piece $3' andthe base` of the pin' '56 Vi's slightly larger than the length. of the shell, While the'distance between the piece d3 and the' point ofthe pin 56 is less than the length of the shell. If. the' shell slides with the open end towards piece 42', it will rest on piece 42, but if it slides with the closed end towards' piece d2, itv will rest on. the pin 5S, As the labyrinth section 2li approaches the four oclock position, gravity causes the shell to drop towards the outer portion of the space between pieces d2' and d3. If the open end is toward piece d2', the closed end moves rst swingingaround the arc of d3, while. if the closed end is toward the pin; 56 the' top is trapped by 43 and the closed end' slides oi the pin into the pocket in Il?. VIn either event, the shell ends up with the open; end Yfacing toward the center of the sorting assembly 3. At about theften oclock position, this shell slides around the outside of 43, be'- tvveen 46 and t9, and then 4lAV and 50 to the resilient disc 4I. At this same position, a second shell enters the jaw 5I to begin the same route. Atv about the twelve oclock position, poppet valve 35j is,l closed by the' rearward movement of tappet' si?, and poppet'valveis opened by forward movementA of tappet 3i; The air in the shell and in the .passageway and the chamber 34 isA thereby exhausted through the shaft pa'ssagewayz.. Byabout the two oclock position, poppet valve 3H is spring closed following the rearward movement'of ltappet 3l. yIfthe shell is sound, and the lips of the open end even, the vacuum in the. shell is maintained and atmospheric pressure keeps; the shell tightly pressed against the resilient disc 4I as the unit continues to rotate. If thel shell is not sound, orv if the lips are uneven or torn,.the vacuum is lost and the shell drops through the passageway. between pecesfd andIlI, and so on out past piece 42`tofthe reject bin 4.-

'.'aibou-t .the .seven oclock position; poppet s valve 35 is opened by forward movement of tappet 38, thus permitting air to enter the shell and chamber 34 through the passageway 39. The movement of the tappets is governed by the curvature of the grooves 32 and 31 in the cam rings 33 and 38 respectively. At this position, piece 49 has pivoted by gravity to close the passageway between it and. piece 46, so that the released shell drops into the space between piece 49 and piece 45. At about the ten ocloclr position, this shell slides down the passageway between pieces 45 and 50, through the shell guiding nozzle 51 onto a pin I0 of the chain 9. Simultaneously, a third shell is entering the movable jaw The shells are carried on the pins IIl under the arm 6I of microswitch 58. The pins IB are slightly longer than the shell, and the microswitch 58 is set to break contact if the arm I9 is raised more than the normal height of the pin and the bottom thickness of the shell. Such increased height could be caused by the interior of the shell being partially blocked, forinstance by a broken punch, or by the lips being slightly compressed so that the shell does not rest properly on the tapered pin. The breaking of contact will stop the machine, thereby permitting the operator to remove the defective shell.

The shells are then carried across the rear of the visual inspection table 65 and are contacted by the slowly-moving shell-rotating belt 64, which imparts a slow rotation to the shell on the pin. Due to this rotation, the operator. by visual inspection, can easily observe any defects such as pitted walls. After passing this point, the shells arrive at the shell ramp `66, which lifts the shells partially off the pins. The shells now pass under the contact arm 62 of microswitch 59. If the shell is shorter than standard the current to the motor is interrupted, permitting the operator to remove the irregular shell. In order to eliminate stoppage of the assembly in the case of an empty pin, the contact arm B3 of microswitch 60 is positioned horizontally so that when an empty pin permits movement of arm 63, microswitch 60 closes a by-pass circuit to the motor.

'Ihe fullyinspected shells are retained on the pins I0 by the shell guide 69 as the pin chain 9 engages the sprocket wheel I I at the end of the inspection assembly and changes direction. 'Ihe ending of the shell guide 69 permits the shells to drop oi of the pins I0 into the receiving funnel I0 and the container 6.

In the foregoing description, any clock positions mentioned refer to the center line of the labyrinth sections 20, and are merely approximations since, within limits, the action points may be varied several degrees in either direction. In the drawings, an assembly having twelve labyrinth sections has been illustrated. The number of sections is limited only by the size of the hopper and the size of the shell, and it is apparent that the number of sections will determine the number of shells inspected during each revolution of the drum.

In view of the fact that the movement of the shells through the labyrinth is entirely due to the force of gravity, the speed of rotation and hopper diameter must be below that at which the centrifugal forces would interfere with the force of gravity. It can thus be seen that for maximum production. a plurality of labyrinth sections is preferable. even though the apparatus must thus be made larger and more expensive. The great advantage in utilizing a labyrinth sorting assembly operative by gravity alone is that the need for mechanical gripping of the shells is eliminated, thereby reducing the likelihood of damage to the shells during the sorting and testing. The assembly is also simpler and cheaper than an equivalent continuous-motion mechanical grip machine.

While the invention has been completely described with reference to the apparatus illustrated by the accompanying drawings, it is apparent that many variations in the sequence of operational steps, construction and design of the structural elements, and the inclusion of additional stages can be made without departing from the scope of the invention. Accordingly, we intend to be limited only by the following claims.

We claim:

1. A shell sorting and testing device comprising in combination a rotatable drum, at least one helical groove on the inner periphery of said drum, a back-plate at one end of said drum, said back-plate being open in the central portion for admittance of blasting cap shells, a face plate at the opposite end of said drum, said face plate having an opening in alignment with said helical groove, a supporting axle centrally-disposed within said drum and projecting beyond said face plate and said back-plate, a motor in engagement with said axle, a stationary housing about said drum, a cam ring attached to said housing,'a cam-operated jaw at the openings of said face plate, at least one labyrinth arrangement on said plate, a cover containing a nozzle over said labyrinth arrangement, at least one vacuum test disc mounted on said axle directly in front of said face plate, a channel in said disc communicating with a valving means for controlling evacuation of air from said channel, a passage within said axle connecting said valving means with a vacuum pump, a passageway in said labyrinth arrangement adapted to guide a shell from said jaw to said vacuum test disc, a passageway in said labyrinth arrangement adapted to guide a shell from said disc outside the periphery of said face plate, and a passageway in said labyrinth arrangement adapted to guide said shell from said disc to said nozzle in said cover, the motion of the said shell being influenced by the force of gravity during rotation of said drum.

2. A shell sorting and testing device as claimed in claim 1, wherein the drum contains a plurality of helical grooves, and an equal number of labyrinth arrangements and vacuu-m test discs are present. I

ADOLPH F. DAUBER. ANTOINE F. GAGNE, JR. CHARLES R. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,359,799 Gerhardt Nov. 23,V 1920 2,278,804. Stuart Apr. 7, 1942 2,337,259 Mason Dec. 21, 1943 2,352,091 Fedorchak June 20, 1944 2,368,796 Ardell Feb. 6, 1945 2,548,645 Ashcroft Apr. 10, 1951 

